Bimetallic olefin polymerization catalysts containing indigoid ligands

Abstract

A catalyst system useful for polymerizing olefins is disclosed. The catalyst system comprises an activator and a bimetallic complex that incorporates two Group 3 to 10 transition metal atoms, which may be the same or different, and a neutral or anionic indigoid ligand. By proper selection of the indigoid skeleton and by modifying its substituents and transition metal centers, polyolefin makers can fine-tune the bimetallic complexes to control activity, enhance comonomer incorporation, and optimize polymer properties.

1. A catalyst system which comprises:
 (a) an activator; and  
 (b) a bimetallic complex comprising two Group 3-10 transition metal atoms, which may be the same or different, and a neutral or anionic indigoid ligand.  
 
     
     
       2. The catalyst system of  claim 1  wherein the activator is selected from the group consisting of alkyl alumoxanes, alkylaluminum compounds, aluminoboronates, organoboranes, ionic borates, and ionic aluminates. 
     
     
       3. The catalyst system of  claim 1  comprising a Group 4 metal. 
     
     
       4. The catalyst system of  claim 1  comprising a Group 8-10 metal. 
     
     
       5. The catalyst system of  claim 4  wherein the indigoid ligand is neutral and has the structure: 
                 
 
       in which each A is independently O, NR, or S; each Z is independently O, NR, or S; R is hydrogen or a C 1 -C 20  alkyl or aryl group; and each of the two rings includes 4 to 7 atoms. 
     
     
       6. The catalyst system of  claim 5  wherein the neutral indigoid ligand is a bisimine in which each A is independently NR. 
     
     
       7. The catalyst system of  claim 6  wherein the neutral indigoid ligand has the structure: 
                 
 
       in which each R is independently hydrogen or a C 1 -C 20  alkyl or aryl group. 
     
     
       8. The catalyst system of  claim 5  wherein the neutral indigoid ligand has the structure: 
                 
 
       in which each A is independently O or NR. 
     
     
       9. The catalyst system of  claim 5  wherein the neutral indigoid ligand has the structure: 
                 
 
       in which each A is independently O or NR. 
     
     
       10. The catalyst system of  claim 1  wherein the indigoid ligand is anionic and has the structure: 
                 
 
       in which each A is independently O, NR, N—, or S; each Z is independently O, NR, N—, or S; R is hydrogen or a C 1 -C 20  alkyl or aryl group; and each of the two rings includes 4 to 7 atoms. 
     
     
       11. The catalyst system of  claim 10  wherein the indigoid ligand is dianionic. 
     
     
       12. The catalyst system of  claim 11  wherein the dianionic indigoid ligand has the structure: 
                 
 
       in which each A is independently O, NR, or S. 
     
     
       13. The catalyst system of  claim 12  wherein the dianionic indigoid ligand has the structure: 
                 
 
     
     
       14. The catalyst system of  claim 12  wherein the dianionic indigoid ligand is a bisimine in which each A is independently NR. 
     
     
       15. The catalyst system of  claim 14  wherein the dianionic indigoid ligand has the structure: 
                 
 
       in which each R is independently hydrogen or a C 1 -C 20  alkyl or aryl group. 
     
     
       16. The catalyst system of  claim 11  wherein the dianionic indigoid ligand has the structure: 
                 
 
       in which each A is independently O or NR. 
     
     
       17. The catalyst system of  claim 11  wherein the dianionic indigoid ligand has the structure: 
                 
 
       in which each A is independently O or NR. 
     
     
       18. A process which comprises polymerizing an olefin in the presence of the catalyst system of  claim 1 . 
     
     
       19. A process which comprises polymerizing ethylene with at least one alpha-olefin in the presence of the catalyst system of  claim 1 .